1. Field of the Invention
The invention relates to a multistage compressor for compressing a refrigerant for an automobile air conditioning system.
2. Description of the Related Art
A multistage compressor is generally used in the art for compressing a fluid to a relatively high pressure. Japanese Examined Patent Publication (Kokoku) No. 58-57635 discloses a multistage compressor for compressing a refrigerant gas for an automobile air conditioning system. Japanese Examined Utility Model Publication (Kokai) No. 63-20864 also discloses a multistage compressor similar to that in JPP '635.
A multistage compressor of the type disclosed in the above publications comprises a cylinder block including a low pressure cylinder bore and a high pressure cylinder bore which are parallel to the longitudinal axis of the cylinder block. A drive shaft extends through the cylinder block along the longitudinal axis. A low pressure piston is slidably provided within the low pressure cylinder bore to define a low pressure compression chamber. A high pressure piston is slidably provided within the high pressure cylinder bore to define a high pressure compression chamber. A swash plate, which is mounted to the drive shaft, engages the low and high pressure pistons. Both the low and high pressure pistons are reciprocated through the movement of a swash plate. The low and high pressure chambers are fluidly connected to each other to provide a two stage compressor.
In the prior art two stage compressor, an unbalanced force is generated on the swash plate and the drive shaft which results in vibration and noise since the compressor of the prior art includes only two compression chambers which are not arranged evenly around the drive shaft and produce low and high pressures in the refrigerant gas.